Automatic multiple crank-pin grinding machine



Sept. 17,- 1935. .Y H'. F. KLINGEL.;

AUTOMATIC MULTIPLE CRANK PIN GRINDING MACHINE Original Filed 'Fama-4, 195o 1I sheets-sheet, i

Sept. 17,1935. H. F. K LINGELE AU'I'OMATLG MULTPLE-CRANK PIN GR-INDING MACHINE 11 sheets-shet 2 original Filed Feb. 24, 1930 ,www M abo Sept. 17, 1935. H. F. KLusELl-z' 2,014,768

'AUTOMATIC MULTIPLE CRANK PIN GRINDING MACHINE original Filed Feb. 24, 1930' 11 lshams-Sheet, 43

Sept. 17, B935. H. F. KLINGELE 2,014,758

AUTOMATIC MULTIPLE CRANK PIN GRINDINGl MCHIN origigal ild Feb. 24, 1930 1 1 sneets-snet 4 Sept. 1 7, 1935.

H. F, KLINGELE 2,014,768

l AUTOMATIC MULTIPLE CRANK PIN GRINDING-MACHINE original Filed-Febfzl, 195o 111 sheets-sheet 5 Sept. E7,- 193.5. H. F. KLINGELE 2,014,768

. .AUTOMATlC MULTIPLE CRANK PIN GRINDINGMMACHINE original Fild Feb. 24`J 1930 11 sheenjs-Sneet 6 l m1' l,

Sept. 417,1935l H. F. KLINGELE. 2,014,768v

I AUTOMATIC MUL'IKIPLE cRANK APIN GRINDING MACHINE Original' Filed Feb. 24. 1930 l1 Sheets-Sheet 7 Original 'Filed Feb. 24, 1930 ll Sheets-Sme?l 8 lAUTOMATIC 'MULTIPLE` CRANK PIN GRINDING MACHINE sept. 17, 193s.

H. F. KLINGELE AUTOMATIC MULTIPLE CRANK PIN GRID'ING MACHINE original Filed Feb. 24', 1930 11 Sheets-Sheet 9 E L E G m L K F. H

Sept. 17, 1935.

AUTOMATIC MULTIPLE CRANK PIN GRI'NDING MCHINE original Filed Feb. ,24, 195o 11 sheets-sheet 1o Sept. 17, 1935. H. F. KLINGELE AUTOMATIC MULTIPLE CRANK PIN'GRINDING MACHINE Original Filed Fb. 24, 1930' v ll Sheets-SheetI ll I Je Patented Sepe-17, 193s UNITED sTATEs AUTOMATIC MULTIPLE CRANK-PIN GRINDING MACHINE Herman E. Klingele, Worcester, Mass., assigner to Landis Tool Company, Waynesboro, Pa., a n corporation of Pennsylvania Application February 24. 1930, serial No. 430,513 Renewed August 30, 1932 sz claims.

This invention relates to a machine for roughgrinding or finish-grinding the crank-pins on crank-shafts for multiple cylinder engines.

The principal objects of the invention are to provide a machine of this character which will grind the crank-pins to a uniform diameter, within the limits usually prescribedfor this class of work, Without handling the crank-shaft after it is put into the machine or other outside. interference; to provide means whereby the machine will grind all the crank-pins and then automatically stop when the' last. pin is ground; to proy vide a machine which will handle varying lengths of crank-shafts for different engines;` to provide for driving the work, and operating the pump which supplies the water used in wet grinding by a separate motor, this motor being the one .automatically stopped when4 the work is completed; to provide means for controlling the motion and location of the-work table by the operator when inserting a new shaft or for experimental purposes', and to provide a construction on which thetable, head stock and foot stocl,"

when once set up with the crank-shaft, will be permanently fixed .with respect to each other thereafter and in which the position thereof on the base is atj all times'under the control of the machine when working on a crank-shaft.

Other objects and advantages of the inventionI will appear hereinafter.

Reference is .to be. had to the vaccompanyin drawings in which Fig. 1 is a front elevation of a'complete machine embodying this invention in a lform to finish grind the crank-pins of a six-cylinder engine;

Fig. 2 is a part sectional view of the feed .box on the line 2 2 of Fig. l and drawn on a larger scale, the cover shown in Fig. 1 being removed;

Fig. 3 is a sectional plan 'view on the line 3-3 of Fig. 1 of the feed box and of the cam lever controlling it in part; v

Fig. 4 is a plan of the complete machine;

Fig. 5 is a partial elevation of the right hand end of the machine; 4

Fig. 6 is a part sectional elevation of the left hand end of the taliie;

Fig. 7 is a sectional elevation of the headstock;

Fig. 8 is an end view of the headstock showing the position of the pinion and intermediate pinion for transmission of motion to the footstock;

Fig. 9 is a section on the line 9-9' of Fig. 'l through the chuck, showing the method of securing the work in the chuck;

Fig. 10 is a section on the line lil- I0 of Fig. 8 showing the pinion and intermediate pinion;

Fig. 11 is a .section on a larger scale on the .Rr-:ISSUED line Il-l I of Fig. 81 showing the giveway stopfor the varying position of the cra'nkpins on the l work; Fig. 12 is a sectional elevation of the footstock; y

Fig. 13 is an end elevation of the same; Fig. 14 is a section on the line lI-M of Fig. 13 showing the mounting of the intermediate pinion; Fig. 15 is a sectional elevation showing the mounting of the'worm, Worm wheel and wheel 10 l upon which the cams are mounted;

Fig. 1 6 is a sectional viewvon the line lB--IB of Fig. 15- showing the friction Idrive between .the

worm and cam wheels; y 1

Fig. 17 is a sectional' elevation on the line ll-l-l 1 15 of Fig. 1 showing the hydraulic cylinder that operates the table, the valve for the same and the stop that automatically stops the table at either `end of its total allowable travel.

, Fig. 18 is a front View of the mechanism con- 2g trolling the movement of the table', showing the table stop cam,l part of the spacing bar and the lever controlling the valve that operates the table;

Fig. 19 is a section on the line IS-I9 of Fig. 18 throughthe hand leverj 2'5 Fig. 20 is a section on the line 20- 20 of Fig. 18 through the adjustable, feature of the' stop;

Fig. 21 is a section on the line 2I-'2l of Fig. 18 showing the rolls on the stop and lever;

Fig. 22 is an end view of the valves and cams 30 that control the angular position of the work;-

Fig. 23 is a cross section of the hydraulic valve used for operating all cylinders except the one -controlling the table;

Fig. 24 is a longitudinal section of the same; 35

Fig. 25 is a part sectional endelevation of the machine,y showing the quick and slow control of feed for the wheel slide, also the wheel drive;

Fig. 26 is a cross section through the center of the steadyrest; 40 Fig. 27 is a cross section on the line `21-21 of Fig. 26 of the steadyrest alone; Fig. 28 is a front relevation of the steadyrest and the cam and lever controlling it;

Figf 29 is a rear view of the truing bracket 45 bolted to the wheel slide;

Fig. 30 is a cross section of the truing bracket on the line 30-30 of'Fig. 29 showing the ratchet gear and screw that moves the truer as much as has been removed in truing;

Fig. 31 is an elevation of the wheel truing-device;

Fig. 32 i's a plan of the wheel truing device showing the parts only that are supported on the `wheel slide; 1 55 sa? 2 4 194e Fig. 33 is s cross section on the line lI-II of Fig.32;

Eig. 34 is an enlarged portion of Fig. 33; and Fig. 35 isa rear sectional elevation showing the connection of the wheel slide with the cam shaft that controls the operation of `the truer.

I prefer to mount thismachine onfa rigidly constructed T-shaped cast-iron base Il ar- 'ranged with an oil reservoir II at the bottom, 'and an open tank I 2, with a removable perfo-t rated cover` I 3, for the grinding liquid.

Mounted on ways I4 on the base is-a slidable table I5 carrying a head-stock It, and a footstock I1. The head-stock is rigidly to theleft hand end of the table. 'I'he foot-stock is adjustably' but rigidly secured to the right hand end`of the table. The three parts, table, head-stock and foot-stock, for all practical purposes, are in one piece when once set up for grinding a particular crank-shaft. The' position" of this unit on the base is at all times under the' control of the machine when working on a crank-shaft. The motion and location of the table can be'controlled also by the operator for the purpose of inserting a new shaft or-for ex' perimenting.

The wheel slide I8 is'carried by a wheel slide block I9 secured to one leg ofthe T-shaped base. A grinding wheel trulng device and also the wheel guard 2l are secured to the wheel slide Il.

I have found it desirable to make a special machine for a crank-shaft with a given throw, and aV` different one for a crank-shaft having a different number of crank-pins. The machine shown isdesigned for a crank-shaft for a six cylinder engine. Three' motors 23,'24 and 2i are used to drive themachine.- The motor 2l drives the grinding-wheel' zc.- 'rne motor u drives the pump 21 to provide and maintain con` tinuous ,hydraulic pressure. These two motors run continuously under 'the control of the v.operator. The third motor 25 drives the work and also the' pump 28 which supplies the water used in wet grinding, and controls'several automatic features as will appear.

The motor 25 is started by the operator every time anew shaft is ready to be ground and is automatically stopped when the grinding is completed for the whole shaft. This motorY is shown as located on a shelf 29 at the rear of the left hand end of the base and belted directly to a pulley on the drum shaft 30. From a drum 3i on this shaft a belt drives a pulley 32 on the spindle Il of the head-stock. 'This belt has to travel laterally along the drum when the table is moved along. The motor 2l is located in an opening provided at the bottom 'of the left hand end of the base. The motor 23 is shown as set up on the floor and belted directly to the pulley shaft n on the wheel slide.

The sequence of operation is as follows: The

operator picks up a crank-shaft by means of lan air hoist or other'v convenient lift and inserts the front end, that is, the one opposite the flanged end. in the chuck 3l at the head-stock. The opposite end of the crank-shaft rests on a movable support'35 which brings it in line with the center. The foot-stock is moved hydraulically, as will appear, so that the shaft is now on the two dead-centers, and the exact location of the first crank-pin has to be-ilxed before the shaft is secured in position. `The center of the steady-rest- 30 coincides 'in lateral position with the center of the grinding wheel.

' predetermined By sliding a gauge over end of the Jaw of the steady-rest, the slight movement of the table to bring the crank-pin shoulders in position tont `the gauge exactly, can be deter,- mined (see Pig. 26). exact length of the crank-pins. .The operator now knows that the crank-shaft is correctly located longitudinally and removes the gauge. 'I'he jaw 43 of the steady-rest is now made to assume a contact position on a correctly located lo pin and held there by another suitable gauge.. The crank-shaft is turned until this contact is obtained, vand the workis secured by a clamping meansL contrlledby a handle l1 and then a pinching handle u at; the foot-mex n` set. 1s This latter handle is arranged to maintain pressure on the centerindependently of the hydraulicpressure.`

During the nishing of the entire crank-shaft the'f'mechanism makes one complete revolution. zo

and `the'work,revolves.,simultaneously, if necessary, tmougnan angieor .120?. Alyieidins means is provided for locking the work in an indexed position. Thisyielding means ,consists of a rod 34 provided with a head 34bagainst which a' spring 3 4@ bears andnormallyforces the head radially inward inw contact with the chuckcarrying the work. Thishead hasa V- shaped rib Il whichis adapted to ,engage a 'similarly shaped recess :orA notch in the chuck or work support I4 for holding vthe same ina o indexed position. Thenl the steady-'rest comes up .agalnst'the work and the wheel-slidemoves` in up to thepointwhere cuttingbegins. This is done by hydraulic pressure.

The `mechanical liney feed has already been 5 thrown in, so grinding commences thereafter. The hydraulic feed-forces the wheel slide in yunder the control of 'a screw as will appear. As the grindingproceeds, the steady-rest is being gradually elevated so that the flnished grindinggw position is reached atzthe` same time by the grinding wheel. Then follows the4 slight holding position .of the grinding wheel again,` and the above operations are repeated over and over un. til theseveralpins are ground. The machine is 55 stopped electrically by crank motion which will be described,'by working the pushbutton re. leasell of s .4 stopping lever. f-

Every time the machine iitops an adjustment is madev automatically,'allowing the wheel slide w to advance one thousandth of an 'inch which represents the amount to be .trued off on thefinishing operation before the next shaft isbegun. Automatic means -is also provided, as will appear, whereby the recessional 'movement of .the wheel 65 slide also, starts the wheel truing' device. The wheel is4 trued after finishing every shaft and. while the work is being changed. Y 'p j As stated, the pump 21. providesthe hydraulic'v pressure by pumping oil from. the reservoir II and distributing it through apipe I l. This pipe delivers the oil under pressure to a two-way valve 52 which .deliversy in accordance with the setting of the valve to eltherof two jointed or nexible pipes 5 3 and M and 'of course the valve 75 mgwgeismadethe's course, there ,is a piston and the piston .rods are l in position by a cap 65 and bolts as shown in Fig. 6.

It will be noticed that^ the distance between the centers of the eccentrics 6| and 62 is the same as the distance between the centerof the eccentric 62 and the center of the shaft 5|. The eccentric 6| has a throw of 'twice the amplitude of the throw of the eccentric 62. Now it will be seen that if the cylinder 56 is supplied with oil under pressure on the right side to forcethe rack 58 to the left, it will turn the pinion 60 and the eccentric 62 through a half rotation. At this time the frame 62 is fulcrumed on the eccentric 6|. Therefore the shaft 5| will be moved axially a distance equal to twice the -throwof the eccentric 62. On the other hand if` the'cylinder.

65 is supplied with oil under pressure the frame 63 will now be able .to oscillate about the eccentric 62 as a center and the shaft 5| will be moved in one direction just as far as the throw of the eccentric' 6 I, that being twice the throw ofthe eccentric 62 the Atwo motions of' the shaft 5| will be equal. l TheA rst of these motions above described isl for the purpose of turning the work 120 and the other for lthe purpose of turning itaseeond 120. -V

Now by reference to Fig. 7 it will be seen that the shaft 5| is provided with a spiralgear 61 work,- ing in a nut68. of a separate steel piece which isl driven in to the spindle' of the head-stock andit isy also pinned-or otherwise fastened so as to constitute a part thereof. lIt is'made separately only for the purpose of economy land this'thread is only practically a thread in this spindle.

The movementcf the shaft 5-| longitudinally therefore causes' it to revolve relative to the spindle 44 actuating the lchuck by `pinion 69 in mesh with pinion 42 thus carrying the work through the areas above mentioned. for the purpose of turning the crank shaft Ato bring the next crank into grinding position.' The end of the crank-shaft is vreceived inv a socket in the headstock 'spindle which has a center 10 for recelvingV it and is held by the clamp controlled by the handle 31 'as previouslyv described. This, of course, is olf center, the amount necessary for the particular crank-shafts being operated upon.

This machine is designed to operate on a stand- -ard crank-shaft and there is no adjustment of course, and head are operated-by the pulleyv whenthe work is to be taken out and move it up This nut is shown in the form :i2 keyed thereto and run by the meter 2s espre-l viously stated. Between grinding operations the work isindexed around by the operation vof the valve 52 which is automatic and which' will be described later.

` The pipe 50 is also provided with a branch valve 12 delivering oil under pressure to either of two pipes 13 and 1| which control a cylinder 15 and its pistonoperating thefoot-stock to draw it back 10 when it is .put in, the operations being similar.

I Two lines along the branch of the pipe, 50 operate through a valve 80, the main cylindery 8| which is connected by its piston rod 08|'xed to the table I5 for operating the latter. This also is all arranged automatically as will appear. The pump 21 therefore operates the four cylinders 55, 56, 15 and 8|, also the wheel slide cylinder 39. 'Ihe headstock spindle is driven from the motor 25. The head stock spindle and the foot stock 20 spindle 85 are each provided with gears indicated at 86. These gears are of -the same size. The gears 86 are connected respectively through intermediate gears withpinions 91 `fixed to a longitudinalshaft 88. The rotation of the head stock 25 will, therefore, impart rotation to the longitudinal shaft 88 and the rotation of thisy shaft 88 willv impart rotation to the foot stockv 85. This preserves the lineup of the two centers and insuresA their simultaneous and equal operation at30 all times and makes them both live centers.

IThe right hand end of thel shaft 88 is hollow' and splined or non-circular to receive a smaller shaft 89 adapted to slidably fit in thehollow end and of course, to be turned positively by the shaft 35 88 whenever the work is 4in motion.- The shaft 89 transmits its rotation throughl a shaft 90 and bevel-gearing 9| to a longitudinal shaft 92 in two parts connected together bya clutch 93 operated by a handlelll. When the two parts of the shaft 40 92 are\clutched together the mechanism in. the feed box 96 is operated for feeding the wheel slide as will appear.

By means of a worm 96 rotation is transmitted from the shaft 92 to a worm gear 91 on a s tud 99 45 (see Figures 15 and 16) This stud is shownas having a bearing at one end only in' a. bracket 99 secured to the frame I0 and as having an ol pocket |00 under the worm. The worm wheel 91 is not 'fixed to the stud but the stud is fixed to its 50 bearing so as .to be stationary. The hub of this wheel 91 is provided with a split collar |02 around it which can be clamped to the hub by an eccentric |03 having an operating handle |04.I A screw |05 is shown on the opposite side for adjusting 55 purposes.

Thescrew |05 and eccentric |03 are mounted in an enlargement |06 cn the hub of a cam wheel |01. Therefore when the parts are in the posivtion shown in Fig. 16 the worm wheel and cam wheel are fixed together to rotate on the stud and when the cam |03 is released the worrn'wheel can I rotate without rotating the cam wheel. 'Ih'is cam wheel is provided in the present instance with four grooves for'receiving cams. In each of these grooves there are six of these cams around the circumference, when the machine isl set up for a. six cylinder crank shaft. In the groove |0| are cams |08, Fig. 28, which control the steady-rest. In the groove |09 are cams |0 -which operate and controi the main cylinder by means of the space bar'therefor, as will appear. In'the groove are cams ||2 for controllingthe operation of the two cylinders 55 and 56 to change the-angle of the 75 crankshaft. Inthesidegroove||2arecams||4 -which control the. operation of the wheel slide.

The cams ||4 engage and operate an arm of a lever H2. Thisleverisconnectedbya link ||2 andthreearmedlever ||1 withthepartstobeoperated. Oneofthesearmsreciprocatesarod ||2 which extends to the rightin Figs. 1, 2 and 3 and in its reciprocatlons operates a' pair of dogs ||2 and |22 for controlling. connection of the shaft 2.2 with the-wheel slid.'- v

The shaft 22 is provided with a-pair of opposite bevel gears |22 adapted to operate afbevel gear |22 in either direction. vConnected with this latter bevel gear is a gear |24 driving a gear |22 on a stud carrying another gear |22 which meshes with a gear. |21 that is' in mesh with a gear |22. On the outside of the fine feed control of the wheel slide, the stud the gears |22 and |22 is adjustable by being mounted on a swinging-arm |22 having a slot connection |22 so that these gears |22 and |22 can be exchanged for gears ofv different sizes to get any desired speed ratio.

with the gear |22 is provided through a yoke |22 entering a clutch collar |22 forv clutching either one of the gears |22 to the shaft 92 or free both of them. 'Ihis is a spring controlled yoke having springsv |24 opposing each other and a collar |22 operated by a tooth |22, as will appear. This tooth is mounted on av lever |21 which extends beyond its pivot and can be operated by hand in the preliminary procs of setting up the machine. A s

lever carries the two dogs ||9 and |22, which are adjustable for obvious purposes, and the link H2 is provided with an'elongated slot |38 toy give a little play in connection with its operation with one of these dogs.

The lever |21 is pivoted at |42 on the frame. The yoke structure |22 is provided with collars |4| on theA two ends which constitute stop surfaces and a pair of latches |42 are provided having abrupt transverse surfaces |44 adapted to" come behind these collars |4| which, when either.

one of them passes a little way inwardly from the position shown in Fig. 2, prevents further motion backwardly. These latches are released by the motion of the lever |21 about its pivot operating cam surfaces on their ends.

It will be seen therefore that when the link ||8 is moved over far enough to take the dog v| I2 back` wardly it swings the lever |21 to the right below its pivot. When it is moved in the opposite direction it will swing this lever in the opposite direction. These two dogs |12 and |22 are adapted.

to be encased bycams |42 and |41 on the hand wheel |42 on which the gear |22 is mounted.

This hand wheel ls mounted'to turn on the axis of the shaft carrying the screw42 but is mounted on a shaft |22 set into the hollow end of the screw shaft. The shatt A|22 carries, keyed to it, a gear |2| which meshes with a pinion |22 vfixed with respect to a'pinion |22. These twopinions are v mounted`on a stud |24n loosely and this stud is Thecn'Il-lmeshe-'syithacircular rack |241.l which,.by means of`bolts\|22.-is fixed to the frame" carried by the hand wheel |42; The two pinions are `of about the samesize but have .diflerent numbers ofteeth, one havingfsevel teethmore than the other".`v

I2 of the machineand therefore is; stationary. The result of this construction isthatthe rota- Ition of the gear |22 is transmitted to the shaft |22 at a very low rate of speed and from thatl shaft to the screw-42 as the shaft |22 is med t0 the shaft of that screw. Thegear |22, in the form shown,

` 9,014,708 I j l makes one completerevolution to .0606 of a revolution of the shaft |22. This gives .623" travel to the wheel slide. ",lhus the'feed of the wheel. slide |2 .is provided for. both automatically and by hand, as the hand wheel |42ris provided with s a handle m for adjusting une para in setting up the machine.` The wheel slide |2 has a downwardly extending bracket to which is pivoted the "end of the pistonvrod of the cylinder 22. Thev l 'screw lis completely fitted to thebearing, which is split on the horizontal plane, the lower half beply releasing the bolt, the cap will hang down and the wheel slide can be bodily raised ollowered into place.

Asthe two cams |42 an |41 come around and |42 operates the-dog |22" th the lever on which both are. mounted,A the feed vis stopped.,.being The control of the connection of the shaft 22 4thrown into neutral, the position shown in ll'lg. 2, l where it remains until the vwheel slide starts to recede. When the wheel slide starts to recede the three armed lever I I1 acts, and the short arm by the link ||2 will pull 'the lever controlling feed gea: into reverse. The feed gear is now reversing while .the other changes are taking place, and it will so continue until the cam |41 adjustably fastened to'the side of the stop feed cam Just described, throws it out of gear into neutral. .Then when the wheel slide is again brought forward, the three armed lever this time acting in the opposite direction will throw the gear into feed, and ilne `feeding will be well on its way before thefeed pecially the setting of the two cams |42 and |41 will control the time of the start'of the fine feeddo of the wheel slide and the time of its stoppage and reverse. lifter reversal of course thewheel slide comes to a stop. Thev rotation of the shaft |22 acts to bring the end of the'screw shaft 42 firmly up against a shoulder |,2I a ball bearing thrust collar being located between them. At this point the grinding wheel-just clears the work. It is' brought to this positimil by the cylinder 22, the action of which' is stop'pedat this point by the cam I |4 and at'once openedup again automati- 60 cally to create full pressure tending to move tbe wheel slide forward. Just :a little before this'the line feed starts automatically.

f' 'I'he -feedwheelv |42 carrying thehandIe is mounted with arunnlng'nt on Vthelshaft |22. The 56 end of theshaft |22 is keyfed so that the icrewxnay alwaysbe driven bytnisfshnft, L l

As the grinding wheel gets slnaller after every truing operation, the position `of the shoulder |2|| is'brought nearer 'the front of the machine 60 for a distance exactly equal,l to the 4amount removed in truing. This' is done by operating on a ratchet gear |24 as thecorrect position is on the horizontal plane. The gear |24 Is-connected to l the outer e`nd of the .shaft-|2251 -On-.the'inner 66 end of shaft is a gearfillwhich' meshes with a gear ||21 formed-as anintegralpart ofthe .sleeve ||22 havinga thread cooperating with a threadednut |29. Every tooth taken up by the ratchet permits the slide 'to' move '.001 inch nearer 70 the front andthus'preserve the correct finishing position of the wheel. 'As the shafts come to this machine from a similar machine doing the rough l. grinding the pins would all be .02,5" or .030 large.

This being so, it would only require. about seven tenths of a revolution of the handl wheel |48 to advance the slide sufficiently to attain .the finish diameter.

The next operation, it vwill be understood, is

the shifting of the crank shaft through atan angle of 120 or whatever is necessary for .the particular crank shaft and these six operations just'described take place vover again. 7.

When lthe three-'armed lever ||1 is moved inwardly at its outer or longer end it operates a linkV |5`|| which is adjustable by a turn buckle. This link operates a valve'||58 which controls the admission of oil under pressure to the cylinder 39 at either end and applies hydraulic pressure to the wheel slide. The object of this, as has been stated, is to operate the wheel slide by hydraulic pressure but to control it by the screw 40.

wheel |01 there is one cam |60 which acts as a stop cam to stop the machine after a coinplete cycle of operations for the purpose of finishing all the cranks on the crank shaft. This operates a lever |65 when the time comes. is an arm |62 which, when the cam operates, the lever opens .an electric contact` 4| in the circuit of the motor and stops the motor.

Atthe same. time the lever |6| actuates an arm |66 which has a tooth |61 thereon for engaging the ratchet wheel |54 and turning it one tooth every time the'machine is stopped. This, through the gearing |56 and ||51 described "above, advances the wheel slide a very small distance, as for example, one thousandth of an inch, after each complete series of operations. This is for the' purpose of compensating for the amount of material taken olf the grinding wheel in :grinding the six cranks, thereby insuring that the next grinding operation will be performed at substantially the same distance from the center within a very small'variation, which is allowable in this class of `work. I

The table |51carrying the head stock and foot stock is'moved forward by the hydraulic cylinder' and a roll |1| on-a stop lever |12 is located in one of' thenotches |10, stopping the bar and table for the time being. When one ofthe cams on Vthe cam wheel |01 engages the nose |13 of the stop lever' |12 it pushes down the roll |1| out of its notch.

The-upper horizontal arm of the bell-crank |12 '.is made in two parts, and adjustably connected together by a double `screw |14 operated by aworm and gear |15. The worm is on a shaft provided with a hand wheel |16'by which it can be adjusted in length.

On the outer yend of the 'bell-crank |12 is a projection t 11. When the bell-crank comes down to bring the stud..|1| out of the notch .I 10 this projection engages a roll |18 on an. arm |19 free on a shaft |80.' A spring |8| vholds this arm On this lever there latch entering the notch in the end of the arm |19 and normally makes it move with the arm |90.

When the time comes to advance the table for the purpose of grinding the next pin, the cam ||0 throws out the stop lever |12 which in turn swings the shaft |80 and the arm |90, which is connected with the arm |19 bythe spring latch 82, so they both move. Thus-the shaft |80 is turned, and by means of'a crank |81, secured on its end inside the base of the machine, and a link |88, opens the valve 80 connected with the cylinder 8| which operates the table. For all of the pins the valve is opened and closed to move the table to the left only. The valve remains open until the roll |\1| slides into the next seat |10 in the spacing bar. Then the valve closes.

It Will be understood that these seats or notches are spaced at distances exactly equal to the spaces between the centers of the crank pins on the work. The length, from the end of the shaft being worked on,`to the center of the first pin is usually standardized, but the location of the pin longitudinally on the machine varies slightly on account of the shaft being hung on the centers and the depths of the centercountersinks lacking uniformity.

After all the pins are ground and the machine is stopped automatically by the stop cam |60, it is necessary to move the table the whole distance to the Vright so. as to be in position for grinding the lrs't pin on a new piece of work., By grasping the handles |83 and |86 and lifting the latch |82 the 'arm |90 is freed from the arm |19 and the operator can move the table at will in either direction without movingup the lever |12. As the handle is moved to the right forthe purpose of moving the table to the right it contacts with a knee lever |89 and depresses the lever |19 that lifts the stop bar |12. This allows the stop bar to drop and prevents its bounding in and out of the notches as the spacing bar passes until the table is stopped. Then the roll |1| is allowed to move into the first notch of the spacing bar.

It may be stated here that only 'five of the cams |0- are required, spaced 60 apart and 60 from the stop cam |60. The last cam ||0 is not needed because of the stop cam |60 which stops the table and machineI as above explained after the lastpin is ground. v

The steadyrest 36 is bolted to the base of the 50 machine in transverse alignment with the. centerV of the grinding wheel and it has sliding contact with the table so that the table can move without moving the steadyrest. The cams |08 on the cam push the roller down and allow the steadyrest to descend on an arc about a pin. 20|. In Figs. 26 and 2 8 theposition at the start of grinding is shown inv full lines. As the grinding process proceeds the cam advances gradually until thev high point is reached, that is, when the grinding is finished. Nowa slight dwell on the cam comes into action on the lever |9|, vand continuing the cam depresses the lever, thus allowing the steadyrest to move .down out of the way to permit the work to pass withoutinterierence. The steadyrest cams like the other cams on the wheel |01 are spaced apart. lThus the steadyrest will be raised or lowered at theright time for en- `wheel |01 operate a'lever |9|. This lever is ar- 5 each pin opposite the grinding wheel. It A understood that the steadyrest is lowered the same-time that the wheel slide is moved With this machine I provide a stone truing device located on the back of the machine out of the. way and permanently attached thereto so that it does not have to be applied a'n'd removed whenever the stone is to be trued. It has been stated herein that thewheel slide is advanced one thousandth of lan inch .after all the, crankpins of each shaft have he'en trued. ofcourse, it is not essential that'this be one thousandth of an inch but that has been adopted as being afconvenient amount. rn praetthat each shaft shall be started with the `stone in a position to grind the crank-pins of the same size on' all shafts; I provide the truing device arrangedito remove one thousan'dth of an inch from the stone after each shaft is completed. By that I mean that the stone is trued down to a total reductionI of one thousandth of sa e ' an inch after the several grinding operations are performed on a single shaft. Oi course, something is removed in the grinding and the truing device removes the remainder of one thousandth yof an inch, if that is the amount decided upon.

"For that reason the wheel slide can be moved up exactly the right amountai'ter each shaft has to apply the truing device to the grinding machine been completed. It has been customary to true the stone after three shafts are completed, that is, after eighteen grinding operations on a six cylinder' shaft and it has also been customary at that time and then remove it before the next shaft is put in and ground. `In this case'thie truing device remains on' the machine all the time and preferably is brought into operation automatically to true the stone after six grinding operations, if it is a six-cylinder shaft that is being operated upon. In this way absolute accuracy is obtained and there is not a great deal for the truing device to do. Furthermore this truing device operates to true the two ycorners of the stone and the face of it-during a single operation and while the work is being ,removed andl replacedso/thatitdoesnot takeup anytime thatoouidbesavedinanyway.

This truing device' acts to true the corners of the wheel to the exact radius called for by the fillets of the crank-pins and it is readily adjustable so that whatever radius these nllets have can be taken care of by lthis truing device without anything but a very simple adjustment. lIt is aleoadiustable in a very simple manner .totake care'of crank-pins of dierent lengths andv consequently stones of` different widths. It can easilybeadaptedtotruethewheeitogreater .quency than has been mentioned.

Of course-the wheel being trued up grows smallerandautomatieallythetruingdeviceis moved up' to provide for this and can conveniently `havee.rangeon-anordinarysiztemachineoftwo incheeeothatawhee'lcanbereducedfour'inches .in diameter automatically and without adjustsoupes 'base frame 241 and give rigid support to the shoe 24U-at all points of its travel.

The feed of the truing device, independent of the wheel slide, is performed hydraulically by a cylinder 2||I. This cylinder is supplied with oil under pressure at its two ends by'pipes 2| I which are Joined to allow for the adjustment. .The supply of oil is controlled from a valve 2|2 which is adapted to be operated to introduce oil under pressure to the two ends alternately. Every time the wheel slide Il moves back, a ratchet pawl 2 Il engages a tooth of a ratchet wheel 2|4 mounted on a shaft 2li. On this shaft is another wheel 2 I8 having notches and a lever 2|! has a roll 2|! and is pressed by a'spring A220 against the wheel 2li. Thus, after 4each operation of the wheel slide, the wheel 2|6and consequently the shaft 2| i is held in fixed position. When the` wheel slide is operated six` times, in the present case, a cam 22| ilxed on the wheel 2| engages the end of a lever 222 andoscillates that lever. This has two effects. In the nrst place this is a threeA arm lever and connected with one arm is a link 223 which operates the valve 2|2 or allovgs oil under pressure to enter the cylinder 2|@ .at one side to .operate the piston therein.

bell crank constitutes a stop/against a plate 2,21 35 4 device. The base frame 241 is; provided with which is movable withthe piston rod 22| o f the cylinder 2|.. At this time it moves the stop so that this plate will engage it towards the end of the stroke when the cylinder operates.

j Movable with the cam 22| is another cam 23|! o one step ahead oi' it. This cam operatesa lever of this -lever is connec by a link 222 with a plate 222. .This plate is moved up by this cam so as to come into contact with the end of a plunger 234 which is pressed down by a springY and pressed up by this plate to cause a spring pawl 22| to engage a ratchet wheel 2 and advence it the distance of one tooth.l 'I'his ratchet '23| similar to one arm df the lever'222. One arm wheel 1s axes on a smut .u1 premiesA with a 50 screw thread 224 operating in a nutl 229 constituting a part of the frame of the truing device. {Ihe frame is advanced one .thousandth of an inch, in the .present instance, for each operation of the pawlv22l.

. f 5 This shaft IIT is also provided with a notched 5 wheel 24| engaged by a spring-'pressed stop 24|. There are Just as many teeth on-the wheel v24| or m amounts with 8mm or less fre.- f u thl'e Ire 0n the ma paw] zl deeignedtostoptheecrew2andinsurethatw man the right place for the-wheel 220 with a parallel rack 2l| movable with it andmeshing withthepinion'orgear2l2.4 The so designed that the double travel of thepistonintbecylinderlllwiilresultinahalf gear is fixed on a stud 252 which carries an arm 2N having a 4 forked end. The forked end of auch der mattothis arm engages ablock or diamond holder 255 'which is 'mounted to slide inv a quadrant path fonned in lone of the pathetinge 2M... "Iheee 75 2,01 two castings are bolted on the shoe 245 and, be-

. ing made in two pieces, they can beadjusted and bolted the right distance apart. The curved part of each casting is provided with a grooved T-slot to receive the diamond holder 255. The'center of the slot has a radius centered aboutwhich the corner of the grinding wheel is described. On

ydi)

each inner end the two path castings are planed to ilt thel sliding block 258.

As the arm 254 turns am; takestho block zus with itthroughan` angle of90' o n the path casting 250, at thebottom-o! Fig. 32', it thencomes .to the straight part of the path casting. Now it moves in this straight path and is guided by a sliding block 2 58 after completing its curved path. 'Then it moves along a straight path into the other casting 250 and finally through the quarter circle at the end of that casting.

This arrangement is provided so that the diamond point dressing the wheel will dress oiLthe corners. The two arcs of the path castings 250 lprovide for the dressing of awheel on a quarter `v circle and the diamond point vis arranged at a proper distance from the center 253 to providev the desired curvature. The two castings are placed far. enough apart so that the straight part oi' the block 258 will just provide for truing the grinding wheel through'out its face.

It will be noticed that on the block ,258 is pivoted a dog 250 at each side and in the path castings 250 there are grooves 26! having a certain extent. When the diamond holder moves into engagement with the block 258 after completing its curved path, the dog 250 on one 4side vhaving dropped into a groove 26|, Fig. 34, at the end of the straight path, it engages the .dog 250at the other end and then the block 25d andthe diamond holder move along in a straight line to the end of the straight path. At that point the dog inaction drops downand the diamond holderwill continue to move in a diierent path, namely in,the curved path of the other path casting 250. The-.block I 258, remaining in the position in which it is left,

is held -in place by a give-way plug 252 located one at each moves. y

y It will; be understood that this series of operations results in moving the diamond -point around the corner of a stone through an angle of 90 While truing and then across the stonev'andaround the, opposite corner 90. When the piston 228 moves end of thestraight path in which it in, thedog 221, attached to thefunderside .ofc the Vco suits, as `the truing operation occurswhile the 'ing purposes.

machine is at a standstill foiloading and unload- It will be seen that theadvantages above vdescribed are securedby this machine.

Although Ivhave illustrated and described-only one 'form 'of the-invention I aware bf the` fact 'l that modifications can be made therein by any .I person `skilled in the art without departing from` `the scope of the invention as expressed in the claims. Therefore, I ,do not win;l to bo limited in thisvrespectfbut what@V do-claim isz--vl In a machine for grinding the crank-pins of table.

crank-shafts, the combination of atable for supporting the crank-shaft to 'be ground, a grinding wheel, means for constantly rotating the grind.- ing wheel, and means for indexing the crank-' shaft around for bringing the different crank-pins 5 in position for grinding, oi'a cylinder and piston connected with the table for moving it lengthwise, pistons-and cylinders connected for indexing, the crank-shaft around, a pump and means'l connected with saidpump for supplying the cylinders with liquid lunder pressure to move the pistons therein for the purposes described.'

2. In a grinding machine, thecombination of a table ior supporting the article to be ground, a grinding wheel, means ior constantly rotating the grinding wheel, and means for indexing the crank-shaft around for bringing the different crank-pins in position for grinding, of a cylinder and piston connected with the tablelior `moving it lengthwise, a grinding wheel slide, a piston and 20 cylinder for operating the grinding wheel -slide toward and from thework, pistons and cylinders connected for indexing the crank-shaft around, an oil pump andv means connected with said oil pumpfor supplying the several cylinders with oil 25 under pressure tomove the pistons therein for the purposes described.

3. In a machine for grinding the pins oi crankshafts, `the combination with a reciprocable table, of a head-stock and foot-stock thereon for sup- 30 porting and turning the work, a spacing bar carried by said table having a series of seats therein arranged at suitable distances apart to control the operation oi the table, a cam wheel, a series of cams thereon, one for reach angie between two.35 crank-pins, and a lever having one arm in position to be engaged by said cams and having means on the other end adapted to engage in said seats` toy stop and hold the spacing bar and also the' i 40 4. CIn a grinding machine,- the combination with a table having` means rfor supporting the work toA be ground, a grindingwheel, a spacing bar adapted to be fixed with respectto the table and having seats therein, a lever having a roll for 45 entering said seats and stoppingthe' table and holding itin fixed position, one arm of said lever, having a double 4screw and a worm-wheel thereon, and a'hand-wheei having a worm for operating the worm-wheelv and adjusting the lengthoi the 50 arm of the lever; r

5.4 In a. grinding machine, the combination with a table having means for Jsupporting the work to 'be ground, a. grinding wheel, a spacing bar adapted tovbe fixed with respect to the table and having 55 seats therein, a lever having a roll forr entering said seats and stopping the table and holding/irnixed position, a cam-wheel having ahseries' of cams thereon for engaging` the other arm of the lever vand. moving the roll out of its seat, a cyll inder having a pistonv connected with said' table i for operating it, meansior introducing liquid into 'saidf cylinder' for moving the table forward to bring'the spacing-bar'ito position for cooperation `with the roll from one seat to the next, and means wherebywhen the roll is brought. out' of its seat 'the application of iluid to said cylinder will be turned'on.

6. In a grinding machine, the combination with. a table for supporting the work to be: ground and a spacingibar carried by' said table and having seats therein at desired intervals, ot a cam actuated lever having'a roll for entering said-seats.

one ata tixneand stopping the bar and' table,` a,

pivoted arm adapted engaged the end' oi said `v out ofits seat, ahand-lev lever and tobe pushed away by it when the roll I is moved out of itsnseat, a cylinder having a piston connected for operating the table, means normaliy connected withfsaid armfor allowing liquid under pressure to enter said cylinderon the side to move the table forward when the roll moves pted to be moved back and to operate said connections-for intro-` ducing liquid on the other side of the piston in the cylinder to move the table back, a latch connection between thehand-lever and the arm, manual means for releasing the latch when the table centeroftheehaftofoneofsaidgea'rs -equaltothedistancebetweentheshafts shaftwillbemoveda aoiavea distance frornthe center-of said shaft to of two gears, wherebywhen the moet remote inderis not working andthe second cylinder working, the head-stock shaft will be moved a distanceequaltotwicethestrokeofthepistonof the intermediate cylinder and when the second or intermediate cylinder is not working and the more. remote cylinder is working,th ehead-stock 10 ce equal. to tlm stroke of the more remote cylinder.

is to be moved back, and means operated by the r11. In a crank-shaft grinding machine. the

hand-lever for forcing the arm away from the first-named lever to prevent said arm forcing the roll back into the seats in the spacing .bar as the table is moved back.

7. In a grinding machine, the combination with a table having means/for supporting the work to. be ground, a grinding wheel, a spacing bar adapted to be fixed with respect to the 4table and having seats therein, a lever having a roll for entering said seats and stopping the table and holding it in i'lxed position, a hand lever having a con'- nection by which it is adapted to reverse the cylinder by operation of its valves when the handlever is turned in one direction, an arm'pivoted on the samefaxis andwilxed with respect to the hand-lever through which said roll operates the plves to stop the introduction of liquid into the cylinder, and means operated by said hand-lever when actuated to move the cylinder back for bringing said arm out of the way, whereby the roll will not be forced back into thenseveral seats as they pass it when the table is moving back.

portion of a revolution,'racks connected with the pistons of said cylinders, gears or pinions bperated by racks, shafts on which 'Said' elll 0l* f5 ions are mounted.. said leverv having therethrough for receiving said shafts, ashft connected with the head-stock having a' viipiral gearthereon, the head-stock having a ilxed thereto meshing with the gear, whe'rsb'y'the M movement of the shaft longitudinally wiii the head-stock spindle, said llever having-a ing forsaid shaft, the distancefrom the of( said shaft to the centr'ofthe shalt'f'd' ofsaid gears'being equal to, the distance 8. In a grinding machine, the combinationwith ',themtlfgthe two gears' them atable and a head-stockA thereon having an eccentric center, of a central spindle adapted to move longitudinally, a spiral gear on said spindle, a nut fitting said spiral gear, means for turning said nut to advance-and retract `the centralV spindle in an axial direction, and means carried by thecentral spindle for operating the eccentric center for indexing purposes.

9. In a grinding machine, the combination with. a reciprocable table, a hydraulic cylinder for operatingthe table, mechanical means for stops ping the table at intervals in its forward travel, means operated by said mechanical means for shutting oi! the pressure frorri` the cylinder,.a

head-stock fixed on the, table, a foot-stock movcombination with4 atable, head-stock vand footably mounted -on the table, a hydraulic cylinder adapted to operate the foot-stock center in an axial direction, means for'supplying liquid under pressure to both of said cylinders. and a valve for controlling the admission of oil for each cylinder. j l0. In .a crank-shaft grinding machine. the

stock for supporting the crank-shaft tobe ground, n eachhavingaspindlaagrindingwheeland meansfor indexing the crankshaft around from one crank-pin to the next comprising a pair of hydraulic cylinders, means for supplying oil under pressure to'the cylinders to advance their pistons Y in either direction, a lever, means connected with said lever for turning the'crank-shaft a portion of a revolution, racks connected with the pistons of said cylinders, gears orpinions operated by saidracks. and shaftsontheleveronwhich'said geancrpinionsaremolmteddaidleverhsving panages therethrough for receiving said shafts andalsohavingashaftconnectedwiththeheadstochmeanswherebythetof-theshaft longitudinally head-stock spindle, said lever having a-bearingfor said shaft. t he :twenty degrees.

so' arranged that when the .inni-mente cylinder operates, the crank-shaft will1be turnedne l,hundred twenty degrees. wherebywhen Y remote cylinder operates, the crank-shaft will be '46" turned through an. arc of another one hundred 12'. 1n a grinding-machine.' the withmeansforsuppotting'the worktobegrmd, means for rotating it, a grinding wheel slidea 4i" grinding wheel mounted on said 'slide,"'means"for mmm 'the grinding iwheel constanilyt draulic. cylinder connected with said wheel slide and, tending constantly to' toward the work, a 'screw-also with 5U-v wheel slide, and means for saidlcrewat-avery slowrateofspeed'tocontrol the action of said cylinder and'v feed'the'v toward the work at a controlled'speedofa'on- .trolling device for the screw comprising'ia gearlie and a ratchet motion for operating slowly. laid gear having a shoulder of the screw bears when the wheel is 'in-ought into position u much the 18.111 a grinding machine,v the 00 with means for supporting the work to be' 'means for rotating it, a grinding wheel a on, and a ratchet motion for operating said gear slowly, said gear having a shoulder against which the end of the screw bears when the grinding wheel is brought into position to-touch the work.

14'. In a grinding machine, the combination with a table and means for supporting the work, means for rotatingv the work on the axis about which the grinding operation is to take place, a

' grinding wheel, a wheel slide on which the grind# slide and table, a cam 'wheel and a pluralityI of series oi' cams on said cam. wheel arranged to control the operation .of the several hydraulic cylinders for operating the table and wheel slide,

-means for'indexing the'work around to bring one eccentric part otit aiteranother in position for grinding, said means comprising -two cylinders and connections wherebyv the operationoi said cylinders will turn the work o n an axis eccentric to thecylinder being ground.' and means iory introducinghuidunder pressure -into the two cylindersinthedesired'order. Y p

16. Ina grinding machine, the combination with a table and means iorsupporting .the work,

I means for rotating the work on the'laxis about which the grinding; operation is -to take place, agrindingw'heel, 'a wheel slide on'which vthe `wheel is. a steady-rest for the work, hydraulic cylinders for operating the wheel 'slide and table. a cam wheel and a plurality of -seriesotcamson-saidc'amwheel arrangedtov control the operation ofthe several hydraulic cylinders for operating the table-and wheelslidej.-V 17. In a grinding machine, the combination k with a table havingmeans for supporting'the work,.a grindingwheel adapted to'be' rotated constantly, a wheel slide carrying the grinding wheel,

a hydraulic cylinder for operating the wheel slide toward 'and from the-work, means for controlling. the iced o! thegrinding wheel by the cylinder,

a hydraulic cylinderior operatingn said table,

means for controlling the latter hydraulic cyling der, and means independentlymounted on the machine 'i'or truing the face and corners-oi the grinding wheel saidlast-named means being automatically operated every time the wheel slide isdrawn back.

18. In a grinding machine, the combination with a table having means for supporting the work, a grinding wheel adapted tobe rotated, a wheel slide carrying4 the grinding wheel, and means independently mounted on the machine for truing the face and corners oi' the grinding wheel every time the wheel slide isdrawn back i'or the purpose or allowing the work to be removed a'nd replaced, vsaid means comprising a pair oiplate's each having an arcuate groove of about a quarter' of a circle and a straight portion, said plates being mountedso that their straight portions are in alignment and being adjustable toward and from each other for diiferent sized wheels, atruing element movable along1 said grooves through'an arc 'oi-180, thus providing for trning iirst one corner or the wheel and then it across the ieee and truing that vand i then truing the othercorner, a hydraulic cylinder, and means connected with said hydraulic cylindervfor moving the .truing tool through the coursel described.

1 9, .In atruing device for a grinding wheel, the

combination of .a pair of plates each having a cam groove curved on an arc of substantially 90 and a'. continuation thereof -at one'end tangent thereto, said plates being right and left handed 4and being placed with their tangents in align- 1Q ment and being adjustable toward and from each other, a block located under saidl platesat the point where they come nearest together to bridge th'e space between them, a truing tool guided to move in said grooves, means for moving said tru- 15 ing tool from a point at the extreme edge of one plate to a point at the extreme edge of the other through an-arc of 180, whereby the truing tool will first true ofi one corner of the stone throughout a quarter circle and will then move across the' 20 face of the stone and true it, and then true oil' the opposite corner to an arc of 90,

20. In a truing device for va grinding wheel, the

combination ol a pair of plates'each having a groove therein, a truing device mounted to move in said grooves, the two plates being arranged right and left hand and spaced apart, a sliding block betweenthem, means for moving the truing tool along said grooves :throughout an arc of 180 to bringit around the corner or the stone, across. its face, and around the other corner, a pivoted dog on each side oi' the block,i said plates'having ,grooves for receiving said dogs shaped so that when the truing tool holder passes into the space between the plates it'willv engage one of said dogs 8 5 and cause the block andl tool holder` toA move as one in straight vline to thev end oi the straight path and so shaped that the` dog drops down allowing -the holder to continue to move along the curved path oi the other plate andthe sliding 40 block to bestopped at -the end oi'the straight 2'1. Ina grinding machine, theV combination with afwheel slide, means for moving the wheel slide back and -iorth tostart and ilnish a grind- `ing operation, a grinding wheel carried by the wheel slide, a ratchet wheel having a plurality oi notches therein, a pawl on the wheel slide vfor operating said ratchet wheel .at each lreciprocation of the slide, a cam tooth carried with the 5 0-- ratchet wheel, a lever in position to be 4operated by the tooth at a predetermined time, a wheel truing device, Aa hydraulic cylinder, means controlled by said lever for allowing fluid under pressure to Venter the hydraulic cylinder,l means oper-l 5s ated by the hydraulic cylinder for'moving the truing toolto true off the grinding wheel. l 22. Ina grinding machine, the combination with a wheel slide, means i'or moving the wheel slide back and forth to start' and iinish a grind- 50.

ing operatioma grinding wheel carried by the wheel slide, a ratchet wheel having a plurality of notches therein, a pawl on the wheel slide for operating said ratchet wheel at each reciproca-` tion of the slide, a cam tooth carried with the g5- ratchet wheel, whereby when the rachet wheel has been turned through an arc a predetermined number of times, the tooth will complete a rev'- olution, a lever in position to be operated by the tooth when the revolution is completed,l a wheel 70 truing device, a hydraulic cylinder, means con'- trolled by saidtooth'ior allowing fluid underpinssure to enter the hydraulic cylinder, means operated'by the hydraulic cylinder, ;f or moving` the truing toolto'true o!! the; grinding wheeL-and u.; 

